Lactifluus volemus in Europe: Three species in one - Revealed by a multilocus genealogical approach, Bayesian species delimitation and morphology

- Multiple species within Lactifluus volemus from Europe are revealed.
- Genealogical phylogenetic species recognition reveals three species.
- Bayesian species delimitation retrieves the three clades with maximum support.
- All species are described morphologically.

This study provides morphological and molecular evidence (from nuclear ITS, LSU, and rpb2 DNA sequences) for three previously unrecognized species within the morphospecies Lactifluus volemus from Europe. Phylogenetic species are supported by both a multi-locus tree-based method and Bayesian species delimitation. Lactifluus volemus and Lactifluus oedematopus are provided with a new description, and a third species, Lactifluus subvolemus, is described as new to science. Lactifluus oedematopus can be easily recognized by its short pileipellis hairs. Both L. volemus and L. subvolemus have longer pileipellis hairs and can only be distinguished from each other based on cap colour. Intermediary colour forms, however, occur as well, and cannot be identified as either L. volemus or L. subvolemus without molecular data. Revealing that L. volemus - already considered extinct in the Netherlands and the Belgian Flemish region, and declining in other European countries - is actually a complex of three species that are even more vulnerable to extinction, this study emphasizes the fundamental role of taxonomy in species conservation.